Electrically commutated, brushless direct current (DC) motors (spindle motors) are inductive motors used in a wide variety of commercial applications. One common application of such motors is in data storage devices, which use the motors to rotate one or more axially aligned data recording discs at a constant high speed (such as 15,000 revolutions per minute, rpm). As the discs are rotated, data transducing heads are controllably moved across the disc surfaces to access concentric tracks to which data are stored.
A spindle motor incorporates a stationary stator portion which supports multiple phase windings which are electrically connected in a star or delta configuration. A rotatable rotor supports a corresponding array of permanent magnets adjacent the windings.
The rotor is rotated by electrically commutating the phase windings in a selected sequence. During each commutation period, drive current is input to one phase, output from another phase, and the remaining phase(s) are held at high impedance.
Market pressures continue to push for electronic devices with improved response times and reliability. As such, challenges remain and a need persists for improvements in the area of spindle motor control, and it is to such improvements that the present invention is directed.